[Asterisk-Users] TE405P hardware question

[Peter Svensson]

On Wed, 22 Sep 2004, Tony Mountifield wrote:

> Does anyone know which physical interrupt line out of the four on the PCI backplane
> the TE405P uses? Or is it somehow configurable by hardware or software?

Depends on both the hardware (electrical traces on the motherboard) and 
software (bios configuration of the chipset).

> My knowledge of how PCI works at the physical layer is rather limited,
> but I believe a PCI card connects to one of four lines, INTA/B/C/D, and
> the PIC on the motherboard then assigns that to an interrupt
> number/level. Is that correct?

A pci slot hasfour interrupts lines, A-D. However, these may be and
frequently are shared with other physical lines. It really depends on how
the motherboard is designed. A common solution on ix86 is to rotate the
signals, i.e. slot 1 pin A is connected to slot 2 pin B and slot 3 pin C
and so on. The combined signal goes to a pin on the motherboard chipset. 
It is acutallu more complicated than that, but you will need to read some 
literature for that. :)

> In the problem system, the BIOS successfully finds the card and assigns
> it an IRQ number, which the driver then picks up, but the interrupt
> count in /proc/interrupts stays at zero. As I said, the same actual card
> is fine in another system.

The Digium cards and/or their drivers does not seem to like having the irq 
shared with other devices. Of course, there can be other problems as well 
ranging from broken hardware to subtle incompatibilities.

Peter